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Vehicle Detection
Dealing with difficult traffic problems that slow emergency vehicles as they travel to their destinations is a dilemma encountered on a daily basis. Anticipating and identifying hazards while responding to incident scenes is critical for ensuring safe arrival.
Deaths in crashes account for a significant proportion of annual firefighter fatalities. Motorists represent the greatest threat to safe and efficient responses by emergency vehicles.¹ Every year in the U.S., there are almost 16,000 collisions involving fire department emergency vehicles. In 2008, Rita Fahy from the National Fire Protection Association's Fire Analysis and Research Division completed a study on U.S. firefighter fatalities in road vehicle crashes from 1998-2007.² She found that overall, crashes, including collisions and rollovers, consistently accounted for the second-largest share of firefighter deaths. The number of deaths annually ranged from lows of 10 in 1998 and 2006 to highs of 25 in 2003 and 2007.
Responding emergency units should make every effort to minimize the risk of injury to themselves and the public. One of the most frustrating things for emergency response drivers is moving through traffic in a timely manner. Many people panic or simply don't adhere to the rules of the road for approaching emergency vehicles. EMS personnel have witnessed instantaneous panic reactions among automobile drivers who, after being approached by fast-moving ambulances with sirens yelping and lights blazing, didn't know whether to stop, swerve, pull over or just keep going.³ Many such drivers become hazards to themselves, other vehicles, and the emergency crews and their patients.³
A complicating issue is that sirens must compete with vehicle noise. Sounds created by engines, drivetrain and exhaust systems, car radios, and vibrations from heating, air conditioning and air intake systems make it hard for drivers to be aware of approaching emergency units. Additionally, the noise-insulating structure of contemporary vehicles has improved over the last two decades. High urban building density is another factor that impacts the effectiveness of siren signals.4
Emergency vehicle operators must always be cognizant that they have little control over the way members of the public react to audible and visual warning devices.5 Studies have recognized that sirens are a limited warning device and effective only at very short ranges and low speeds.6 At speeds above 50 mph, an emergency vehicle may "outrun" the effective range of its audible warning device.7 In 1991, Drs. Robert De Lorenzo and Mark Eilers reported that U.S. Department of Transportation studies indicated that over a siren's effective frequency range, the average signal attenuation through closed windows resulted in a maximal effective siren-penetration distance of only 26-40 feet at urban intersections.8 Findings showed that sound penetration did not leave sufficient time for a driver to adequately respond to emergency warning signals.9 Siren tones are typically nondirectional, and the time taken to search for and locate the emergency vehicle after hearing the siren is a crucial factor in decreasing the reaction time.10
Reducing response times by emergency services is vital. The Early Emergency Detection System (EEDS) is designed to assist responders by giving an early warning signal to motorists that emergency vehicles are approaching. The ability of other drivers to detect and safely avoid emergency vehicles is crucial to collision prevention.11
How EEDS Works
With EEDS, emergency vehicles are equipped with a transmitter to send an electronic warning signal ahead of the unit. The driver activates a switch to send out the signal. The public can pick up this signal with a receiver plugged in to a cigarette lighter. The receiver will have a blinking light, buzzer and recorded message to inform the driver that an emergency vehicle is approaching. When the vehicle ignition is turned on in new-model vehicles, the EEDS will be reception-ready. The plug-in receiver operates independently of the car's radio, and the radio does not need to be on for EEDS to provide the early warning.
If the emergency vehicle is traveling at 40 miles an hour, the public will have approximately 20 seconds to clear a lane by pulling over to the right. This will allow the emergency vehicle a free lane to continue to its destination.
The inventor of EEDS is Ralph Pickens from Kingsport, TN. Pickens had an experience with a responding emergency medical unit as he was on his way to the local post office. He was inspired to find a safer and more efficient way for emergency responders to deal with traffic problems. He conceived the idea after discussions with local emergency personnel.
Greg Duncan, maintenance division director of the Tennessee Department of Transportation, says EEDS falls into the category of intelligent transportation systems (ITS), since it is providing communications from vehicle to vehicle. According to Duncan, EEDS devices appear most effective when all vehicles are equipped, and a national effort should be spearheaded by groups such as the Intelligent Transportation Society of America, Federal Highway Administration and National Highway Traffic Safety Administration. This would allow for standards to be developed and strategies formulated for a nationwide implementation.
EEDS has been sent to the U.S. Department of Transportation and the Department of Homeland Security for consideration as a viable safety technology, and a U.S. patent application has been submitted.
Experimentation
Pickens built a transmitter and receiver for testing and demonstration purposes. He plugged the receiver into a car's cigarette lighter. The transmitter, which was approximately three-quarters of a mile away, transmitted a signal that was picked up by the receiver. The first warning signal is a red blinking light that will aid people who are deaf or hard of hearing. A buzzing sound is then activated, followed by a recorded message that states: "An emergency vehicle has been detected."
The demonstration frequency used in Pickens' initial trials came from the public domain. He recommends a higher, restricted frequency ultimately be used for EEDS that would not interfere with other frequencies. The U.S. government will need to set standards for the frequency coverage.
It is important that all states be on the same frequency. The public can be equipped to receive the emergency signal without the need of a dial selector, regardless of which state they're in. A radio band, either AM or FM, consists of many frequencies. A dial selector is needed to obtain the station you wish to tune in to. EEDS would operate on only one frequency, independently of the vehicle's radio. This would allow the emergency signal to be received even if the vehicle's radio is off. There is no need for a dial selector because only one frequency is involved. It would be important to simplify the process by having a standardized frequency for all states. The public would be equipped to receive the signal regardless of state. Also, by using a higher, restricted frequency, EEDS would not be disruptive to television or cable networks.
The goal is for the public to be able to purchase temporary plug-in receivers for current vehicles. In the future, new arrivals from the factory can be equipped with EEDS. Once the EEDS frequency is established, engineers can work with automobile manufacturers to work out the technical matters relating to placement of the equipment and uniting the receiver with the vehicle's radio to operate as one unit physically, but remain technically independent. Pickens says the size of the equipment will vary depending on the frequency selected.
Conclusion
The cost of emergency vehicle collisions is estimated to be in the millions of dollars and constitutes the greatest cause of monetary liability within the industry.12 EEDS has the potential to reduce accidents, benefiting the public, insurance companies, and city and county governments. The inventor of the EEDS welcomes questions and comments; contact Pickens at rpickens@eedsystem.com. Find additional information at www.eedsystem.com.
References
1. DeLorenzo RA, Eilers MA. Lights and siren: A review of emergency vehicle warning systems. Ann Emerg Med 20(12): 1,331-5, Dec 1991.
2. NFPA. www.nfpa.org/assets/files/PDF/OS.FFVehicleDeaths.pdf.
3. Wolfberg D. Lights and siren and liability. J Emerg Med Serv 12: 38-40, 1996.
4. Ibid.
5. Emergency Warning System Products. www.ewsp.com.au/research.
6. International Fire Service Training Association. Pumping Apparatus Driver/Operator Handbook, 2nd Ed., 2006.
7. Op. cit., DeLorenzo, Eilers.
8. Op. cit., International Fire Service Training Association.
9. Op. cit., DeLorenzo, Eilers.
10. National Academies of Emergency Dispatch. www.emergencydispatch.org/articles/warningsystems1.htm.
11. Killeen J. The theoretical and practical aspects of visual warning methods in use on emergency vehicles. www.ambulancevisibility.com.
12. Op. cit., DeLorenzo, Eilers.
13. Houser AN, Jackson BA, Bartis JT, Peterson DJ. Emergency responder injuries and fatalities: An analysis of surveillance data. Rand Corp., www.rand.org/pubs/technical_reports/TR100/.
Mark J. Finucane is an assistant chief with the Johnson City (TN) Fire Department, in charge of its operations division. He is a commissioner with the Tennessee Commission on Fire Fighting, Personnel Standards and Education, and is currently enrolled in the Executive Fire Officer program at the National Fire Academy.
